The Runtime Engine
Chapter 3 focused on the plans that the CBO made. It is now time to look at how those plans work out in practice. I will explain the traditional ways of gathering and analyzing runtime data as well as a newer complementary approach called the SQL performance monitor. To fully understand SQL performance, it is very important to understand the role of workareas and the shortcuts the runtime engine uses to minimize overhead, and both of these topics are covered in this chapter.
Collecting Operation Level Runtime Data
As you’ll learn in Chapter 5, we almost always need to get a breakdown of the behavior of an SQL statement ...